The effect of treatment of various strains of influenza virus with glycosidases will be studied. Attention will be focused on the effect of glycosidase action on chemical composition, infectivity, hemagglutinating capacity, neuraminidase activity, serological activity and immunogenic specificity of the viruses. The occurrence, chemical nature, specific location, and possible function of non-Forssman host antigens found on the surface of influenza virus particles will be investigated.